08-10 SS Turbocharged General Discussion Discuss the 2008 - 2009 Chevy Cobalt SS Turbocharged. On sale since the second quarter of 2008.

NLS boost pressure drop

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Old Aug 7, 2009 | 12:35 PM
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boosting in Ohio's Avatar
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From: Kent, OH - Cleveland
NLS boost pressure drop

Hey yall, been lurking on this site for a few months, and finally decided to make an account. now, I've been trying to get this NLS down for quite some time, but it just doesn't seem... right. Every time I NLS, my boost pressure will dip from 15PSI to roughly 5-10PSI.Is this normal? has anyone else experienced this? From my understanding, I thought the pressure was supposed to stay @ 15PSI... any info would help guys, thanks!
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Old Aug 7, 2009 | 12:41 PM
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09turbo's Avatar
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From: Charlotte NC
welcome to the site. and when i NLS i dont really see that much or a pressure drop. just make sure your doing it fast enough
but not too fast and break a shift linkage like i did
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Old Aug 7, 2009 | 09:05 PM
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boosting in Ohio's Avatar
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why thanks for the welcome, so in your opinion, is that normal for my boost gauge to dip down to about 10 psi when shifting? or should it stay put on 15...
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Old Aug 7, 2009 | 10:39 PM
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You have to be quick to keep the boost up there. When you clutch in, you are taking the load off of the engine. Even tho your revs stay up, it doesn't take much fuel to keep the engine going fast because the load isn't there. Less fuel means cooler exhaust. Cool exhaust means no heat for the turbine. No heat for the turbine means no compression, which means no boost. There's your thermodynamics lesson for the day. You can see this if you use cruise control on hills. As you go uphill, your boost increases even though your revs stay the same. If you go back downhill your boost will drop to vacuum, but again your revs stay high. Think of clutching in as you shift the same as going downhill.

In reality, the NLS is just something to keep you from over-revving the engine when you shift.
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Old Aug 7, 2009 | 10:44 PM
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OneCOLDBIZL272's Avatar
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i think you have .3 seconds to make the NLS, if you fail to do it that quick it will drop.
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Old Aug 8, 2009 | 06:53 PM
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From: NC
^^^What he said. The boost will remain constant if the NLS is done correctly. Also you should hear 1 pop from the exhaust. If you hear more than one, then you didnt shift fast enough. Welcome to the forum.
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Old Aug 8, 2009 | 10:14 PM
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From: Rio Rancho NM
Even with my trifecta tune the boost stays peaked at what Vince has it set at. It's a bit more rough on the car from 2nd to 3rd, but the boost stays peaked and doesn't drop.
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Old Aug 9, 2009 | 12:40 AM
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boosting in Ohio's Avatar
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From: Kent, OH - Cleveland
haha, I successfully pulled a NLS today!!! I think that my problem was that I was either letting off of the gas as I shifted a little bit (as it seems so unnatural), or I wasn't pushing the clutch down all the way. Well, now that I got that down, I think its time to exploit the other wonders of my car.. maybe a tune here, a nitrous bottle there...
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